A currently known swivel chair tray consists of an upper tray, a lower support beam, a support shaft and spring device components, wherein the swivel chair can make proper pitching around the support shaft just after the upper tray and the back of a swivel chair seat are fixed, which can make a user feel comfortable. A Chinese patent (Publication Number of Grant: CN 2587252Y) discloses a tray, which mainly comprises a base plate, a movable seat, a tapered tube and an adjusting device, wherein the movable seat is fixedly connected to the base plate, a tapered tube fixing plate is provided on the other side of the movable seat, and the taper tube fixing plate, the movable seat and the tapered tube are fixedly connected; the adjusting device comprises an adjusting rod, an adjusting plate, a torsion spring, and a torsion spring fixing plate, wherein the adjusting rod is inserted in the movable seat, the adjusting plate is fixedly connected to the end of the adjusting rod that is inserted in the movable seat, one face of the adjusting plate is in contact with an air pressure rod, and the other face is connected to the torsion spring; the other face of the adjusting plate is provided with an adjusting plate rotation stopping pad; the movable seat is riveted to the base plate with a rivet, a tapered tube is welded in the central position of the movable seat, the torsion spring and the torsion spring fixing plate are both wound on the rivet, one end of the torsion spring is fixed on the torsion spring fixing plate, and an adjusting plate blister is provided on the adjusting plate; the tray is provided with a locking mechanism, and the locking mechanism mainly comprises a fixing block, a rivet, an adjusting rod, a roller seat, a roller, a roller pin, an adjusting sleeve, a rivet, an adjusting bolt, a compression spring, a fixing seat, a brake pad, a steel sleeve, and a locking nut; the fixing block, the end of which movably penetrates into the rivet, is fixedly connected to the movable seat; one end of the brake pad is movably fixed in the center of the rivet, and the other end of the brake pad is provided with a long kidney-shaped hole; the adjusting bolt penetrates into the hole, wherein one end of the adjusting bolt is screwed with a locking nut and sleeved with a steel sleeve, the outer surface of the steel sleeve movably matches one side of the fixing seat, the fixing seat is fixedly connected to the base plate, the other side of the fixing seat is fixedly connected to the adjusting sleeve, and the compression spring is in clearance fit with the inner side of the fixing seat; the compression spring is wound around the adjusting bolt, the end surface of the adjusting bolt is pressed against the roller, which is riveted on the roller seat with a roller pin, a rivet penetrates into the side face of the roller seat, and the side surface of the roller seat is in movable connection to the adjusting sleeve; the adjusting rod is welded at the inner side of the other end of the roller seat. However, such a swivel chair tray cannot adjust the angle of the torsion spring, so the adjustment degree of the seat cannot be changed and the operation is relatively inconvenient.